This invention relates to electrostatographic cleaning apparatus, and more particularly, to an effective, long-life blade-cleaning apparatus having means for removing trapped particles therefrom.
Electrostatographic process equipment, which produce or reproduce toned images on selected substrates by employing electrostatic charges and toner particles on an image-bearing surface such as an insulated photoconductive surface, typically operate through a sequence of currently well known steps. These steps include (1) charging of the insulated photoconductive surface with electrostatic charges, (2) forming an electrostatic image on such surface by selectively discharging areas on such surface that are the equivalent of the background of the image being formed, (3) developing the electrostatic image so formed with particles of toner, (4) transferring the toned image to a suitable substrate for fusing, and (5) cleaning the image-bearing surface by removing residual particles and fibers therefrom in preparation for similarly reusing the surface for producing another image.
The quality of the images produced by such equipment depends significantly on the ability to clean the photoconductive surface before it is reused.
Several types of cleaning apparatus, including blade-type cleaners as disclosed, for example, in commonly assigned U.S. Pat. No. 3,706,108, issued Dec. 19, 1972 in the name of Taylor, have therefore been developed for cleaning the photoconductive and other image-bearing surfaces in such equipment. The life and long-term effectiveness of such blade-cleaning apparatus, however, depend significantly on how close to the surface, and how free of trapped particles and fibers, the cleaning edge of each blade is.
This is because particles and fibers, trapped on or between the cleaning edge of a blade and the surface being cleaned, tend to space the cleaning edge from such surface, thereby resulting in poor and ineffective cleaning. Furthermore, such trapped particles and fibers also undesirably cause non-uniform wearing and scratching of such surface, for example, an image-bearing surface, which then results in poor image quality.
Conventional mechanisms and attempts to minimize the detrimental effects of particles and fibers being trapped between the cleaning blade and the surface being cleaned are disclosed, for example, in the '108 patent and in U.S. Pat. No. 4,295,239. Such attempts have included, for examples, use of plurality of continuously rotating cleaning blades, and of a passive flicker bar which, in turn, cleans each rotating blade during such rotation. It has been observed, however, that such conventional mechanisms are only minimally effective, and that they frequently have to be replaced due to cleaning failure or due to damage to the surface, especially an image-bearing surface.
Additionally, it has been found that the trapping of residual particles and fibers between the cleaning edge of a cleaning blade and the surface being cleaned is, in significant part, a function of several factors. These factors, for example, include: (a) the cleaning angle the blade edge makes with such surface, (b) the effectiveness of the seal at such an angle between the cleaning edge and the surface, (c) the normal force applied by the cleaning edge to the surface being cleaned, and (d) how long fibers remain trapped, as well as how well such trapped fibers are removed from a cleaning edge before such edge recontacts the surface being cleaned. Conventional cleaning apparatus as disclosed in the '108 and '239 patents are therefore limited for examples because a continuously rotating cleaning blade makes only a momentary contact and seal with the surface being cleaned, and because some particles and fibers that are trapped on the blade during cleaning, due to a lack of mass for instance, cannot be removed from the trapping edge by a mera passive blade flicker.